• Welcome to the forum website of the Vincent H.R.D. Owners Club.

    Should you have any questions relating to the Vincent H.R.D. Owners Club, or Vincent H.R.D. motorcycles in general, please contact Graham Smith, Online Forum Webmaster by calling 07977 001 025 or please CLICK HERE.

    You are unrecognised, and therefore, only have VERY restricted access to the many features of this forum website.

    If you have previously registered to use this forum website, you should log in now. CLICK HERE.

    If you have never registered to use this forum website before, please CLICK HERE.

Norvin front carb clearance

edward

Forum Website User
Non-VOC Member
Most Norvins have a problem with clearance of the front carb. with the bottom of the tank usually requiring a cutaway or an extended serpentine manifold to move the carb. down or out. I have a rather elegant solution which seems to work quite well. I have a 3/8 I.D. fuel hose which is clamped onto brass connectors fixed into the tank at either end. This line runs into the tank from the front and exits directly above the carburettor. The throttle cable slides neatly through this tube which allows an easy run throttle to slide without any kinking. I have a fibreglass tank which made drilling holes and fixing the connectors quite easy but the same principle could be used to modify a metal tank. The downside is that some dexterity is required when removing the tank as the carb slide has to come out at the same time. I have Mk 1 Concentrics which are fairly tall in fact on my bike the top half centimetre of the carburettor is actually in a recess in the bottom of the tank.
Regards
edward
 

bmetcalf

Well Known and Active Forum Website User
VOC Member
This sounds very interesting. Where does the cable emerge on top? Can you post a photo? Do you have ethanol in your petrol in Oz and has it affected the tank inner surface?
 

davidd

Well Known and Active Forum Website User
VOC Member
Edward,

I have thought about this many times when making tanks. It is good that you found this solution as a stuck slide can give a scary ride.

I have made a few original style Egli tanks and of course, they have a mounting hole that goes straight through the tank which seems to prove the principle. There are two down sides: first, adding places for a leak to occur and second, which you mention, is removing the tank requires the cable to come with it.

For anyone who is still it the fabrication stage of building a Norvin, or a custom, I would urge that the fabricator add space to the tunnel to route the cables. I did this with a steel Vincent tank that I made for my Flash. It has the advantage of being able to take multiple cables and wiring. On mine I made the dome above the carb as high as I could and then ran a chase to the front of the tank. This has the advantage of more room and being able to remove the tank separate from the cables.

On fiber glass tanks you can also glass in a fiber glass tube. Unlike your tube of gas line, the fiber glass tube will be straight, but in most instances a slight bend is better than a sharp one. I would take som 1/2" steel tube and wrap the desired length in wax paper. Then wet out the cloth and wrap it around the tube. Then take some more wax paper and wrap it around the whole mess. When cured, the wax paper will peel off the outside. I usually take a piece of scrap and drill a 1/2" hole in it, open the vice to give support the scrap and pound the steel tube out being careful not to distort the hammerd end of the tube. Once it starts it will usually come out. You can re-arrange it on the vice and pull it out. Make the fiber glass tube a little longer than necessary so you can damage the ends when removing the steel tubing. Drill the holes in the tank and glass the tube in which should be not more difficult than glassing in the fittings.

GreyFlashTank002.png


David
 

clevtrev

Well Known and Active Forum Website User
VOC Member
Jeff Barkes was using tubes through the tank to guide his cables, in the seventies. That was on his standard Vincent.
 

edward

Forum Website User
Non-VOC Member
Hi Bruce,

The tube actually enters the tank at the bottom front of the tank curves towards the top then down onto the carby. So the cable actually goes through a sleeping 'S' route from throttle to slide but the cable slides very freely. I don't have photos(maybe next time the tank comes off) but might draw a diagram if people are interested. The high octane petrol is ethanol free and I have been assured by Shell that there are no plans to change this. Most of the 91 octane is E10 and the straight regular petrol is being phased out.
Regards

Edward
 

ogrilp400

Well Known and Active Forum Website User
VOC Member
G'day Ed,
As a builder of two Norvins I found that the problem is more to do with the clearance between the carby, frame tube and rear cyclinder head fins. The cable can be routed through a tube that U turns out the top of the carby.

Phelps.
 

Chris Launders

Well Known and Active Forum Website User
VOC Member
Hi there.
Instead of running the cable right to the carb i have used a short length of curved stainless tube with a thread at one end to screw into the carb top and a sleeve at the other for the cable outer.You can use quite a sharp bend this way and there is no risk of the cable kinking.This works really well on standard twins as well.
Chris.
 

BigEd

Well Known and Active Forum Website User
VOC Member
VOC Forum Website Moderator
Like Chris I have used a metal tube on the cable of the front carb top of my Rapide to improve the cable run. I've also put a piece of tube on the rear carb top to give a better radius there.
I have seen a picture somewhere of a tube welded through the UFM at an angle from one side to the other. That looked like a good solution to improving the cable run although I don't know how well it actually worked.
Hi there.
Instead of running the cable right to the carb i have used a short length of curved stainless tube with a thread at one end to screw into the carb top and a sleeve at the other for the cable outer.You can use quite a sharp bend this way and there is no risk of the cable kinking.This works really well on standard twins as well.
Chris.
 

roy the mechanic

Well Known and Active Forum Website User
VOC Member
On mine i used a peice of car brake tube bent to 90degrees , swaged to take the cable, also a hand made carb mounting to give 4x fag papers clearance at the frame + 5x fag papers at the rear head. Doubled-up for the rear, gives a nice smooth action, also seems to impress those who have seen it!
 

jim burgess

Well Known and Active Forum Website User
Non-VOC Member
Gentlemen, this is all really interesting! How about a few photos that I can add to the files so we can all clearly see what you are doing? Please?
Cheers
Jim Burgess
 
Warning! This thread is more than 11yrs ago old.
It's likely that no further discussion is required, in which case we recommend starting a new thread. If however you feel your response is required you can still do so.

Top